When comparing MultiMarkdown Composer vs Texts, the Slant community recommends MultiMarkdown Composer for most people. In the question“What are the best Markdown editors for OS X?”MultiMarkdown Composer is ranked 13th while Texts is ranked 16th. The most important reason people chose MultiMarkdown Composer is:

Pro

Fast syntax highlighting

Pro

Highly customizable

Pro

Counts words, characters, lines

Pro

Can show invisible characters

Pro

Supports multiple Markdown dialects

Unfortunately, this is a global setting for save (it can open any dialect)

Pro

Immediate Markdown rendering and preview

Texts immediately renders the formatted Markdown as you are typing it inside the text box. It's quite similar to a WYSIWYG editor.

Pro

Imports and exports many formats

HTML, Word, TeX, PDF, ePUB, OPML.

Pro

Works on Mac OS X and Windows

Cons

Con

Table of contents gets out of sync sometimes

If you keep the auto-generated table of contents open while you work it gets out of sync, meaning items in the table of contents (at the end) disappear until you restart the program.

Con

The way the preview shows images is inconsistent

The preview is a bit inconsistent with images. Sometimes it shows the image correctly, sometimes it shows a blue question mark.

Con

Overwrites standard Markdown

Editing a preexisting Markdown document overwrites standard markup in it (for example, interpreting headings marked with leading "#"s and rewriting them with a trailing underscore line), adds extra blank lines between all paragraphs, and adds extra spaces at the head of unordered-list items.

Con

Spell checking is not activated by default

There's a built-in spell checker which is not activated by default and is quite hidden.

Con

Limited choice of built-in themes

You can download the CSS for these themes and create your own, but would be nice to have more flavors (e.g. GitHub)